Sorption properties of individual constituents of Devonian shale were compared with similar properties of a wide variety of shales of different lithologies. Major components examined included illite, quartz, chlorite, kerogen, and oil. Kerogen was isolated from a core sample retrieved from a producing gas well, while the oil used was taken from a gas well in West Virginia that is producing from the shale interval. Helium and methane isotherms were collected up to 1000 psia for analysis of the adsorptive properties of these substances. It is shown that about 50% of the gas in the rock is associated with and stored in the open porosity of the rock. The remaining 50% is more intimately associated with some of the mineral or organic constituents of the shale. Some of the gas is dissolved in the oil which serves as an efficient storage material. In addition, the solid kerogen can also store gas by adsorption, as can other minerals, such as illite. All materials examined contributed to the total sorption isotherm, with smaller amounts being associated with storage in quartz and chlorite. This total isotherm is, however, less than the composite isotherm obtained by summing the separate isotherms of its constituents. This implies a possible blocking phenomenon that reduces the storage efficiency of the minerals.

You can access this article if you purchase or spend a download.